Allen will join the same Heat team that defeated the Celtics in last year’s Eastern semifinals en route to an NBA title. Although he said the next meeting with the Heat, which happens NBA opening night, will be “weird,” Pierce holds no malice toward Allen.

"Ray made the best decision for him," Pierce said. "That's what it's all about: You get in these situations, you become a free agent and you make a decision based on what's best for you and your family. Ray will always be a brother for me. If it wasn't for him, I probably wouldn't be wearing a championship ring. So the things he was able to do for this organization will never be forgotten."

Allen and big man Kevin Garnett joined the Boston Celtics prior to the 2007-08 season. The move paid immediate dividends and the Celtics won the 2008 NBA title over their rival Los Angeles Lakers. In his five seasons with the Celtics, Allen averaged 16.5 points and shot 41.3 percent from the 3-point line.

But Allen turned down a two-year, $12 million offer from the Boston Celtics to make about half that per season in Miami, where he will earn a mini mid-level that pays about $3 million over the three years of his deal.

Despite his obvious contributions, injury and a rocky relationship with point guard Rajon Rondo marred Allen’s final season with the Celtics. Allen also was moved to sixth man as the Celtics made room in the starting lineup for rising guard Avery Bradley.

"People can use all the Rondo stuff—and it was there, no doubt about that—but it was me more than Rondo," Rivers said, per Wojnarowski. "I'm the guy who gave Rondo the ball. I'm the guy who decided that Rondo needed to be more of the leader of the team. That doesn't mean guys liked that—and Ray did not love that—because Rondo now had the ball all the time. ... ”

He will play without Allen, the man he called “a brother,” but Pierce is pleased with the moves made by Celtics president of basketball operations Danny Ainge. The Celtics signed Garnett to an extension and will have new additions Jason Terry and Courtney Lee in the backcourt. A healthy Jeff Green also could help out with the loss of Allen on the wing.

"I love what Danny's been able to do," Pierce said. "It was a tough decision this summer. A lot was riding on what direction we were going to head in. It was just a domino effect, once we signed Kevin, we knew were going to try to make another run at it. That's pretty much the way I looked at it. Once we signed him, a number of guys were able to jump on board.”